Hydraulic brake systems are used on most automobiles and many trucks. In such systems there are either brake shoes or brake calipers which engage a brake drum or brake disc. The service of brake drums and discs places them under substantial forces which invariably lead to distortion and lack of circularity. When this happens the brake shoes or discs are unable to brake as effectively because they tend to hop or skip off of the high points on the distorted brake drum or disc. The noncircularity of the drums and discs also cause pressure waves in the hydraulic brake systems which can further aggravate easy control of the system. Brakes also tend to lock more easily because of the cyclical increases in the forces between the shoes and the drum.
It has been previously known that a small accumulator or pressure equalizing device is effective for reducing pressure surges in hydraulic braking systems. Such devices are also effective in helping to equalize the pressure experienced by each brake cylinder. U.S. Pat. No. 3,430,660 to Mitton shows such a pressure equalizer apparatus. The Mitton invention has a resilient bulb which is held within a housing. The bulb is contained within a concave void which allows the side walls of the bulb to flex outwardly when greater pressures are experienced in an interior bore. Although this design has proven to be useful, it has suffered from limitations and failures, including early failure of the resilient bulbs and sealing failures between the bulb and the housing components.
Failure of the resilient bulbs has been analyzed to determine that bulb flexing exceeds a desirable range for the size and type of resilient material being used. It has also been found that cracking occurs because of the stress arising at sharpened points of engagement between the bulb and the surrounding housing. The current invention seeks to solve the bulb cracking problems by providing a bulb and housing which are specifically designed to cause the concave area around the bulb to become pressurized when the accumulator is assembled. The invention is also directed to providing a superior seal arrangement so that the accumulator does not leak either air or hydraulic fluid. Other objects and features of the invention will be given in the following detailed description of the invention.